Automatically adjusting fork



Apl 27, 1954 J. l... LEPKowsKl 2,676,672

AUTOMATICALLY ADJUSTING FORK Filed Feb. 20, 1953 2 Sheets-Sheet l April 27, 1954 File@ Feb. 20, 1953 J. L. LEPKOWSKI AUTOMATICALLY ADJUSTING FORK 2 Sheets-Sheet 2 ATTO RN EY Patented Apr. 27, 1954 .as eTAwTl-:s PATENT Application February 20, 1953,` =Serial^ N o; 337,960

7. Claims.

l This invention'elatesfxtogindustriali truckszof the :class v'havingtailifting::r:arriage that Vmoves lirertically; to .liftnasload. l-Itfhasfbeen :proposed Ato maken'v vertically. adjustable the. members :through :which .the liftingcarriageaactuallyflifts' the load member.

than one .upperffpositionvon the liftingvcarriage.

V.f2 a ffurtherfieaturetof; myfin-vention; I provide means; that, When' the.' detent: imoves tof release position, positively .-locks v the detent :in -`release position. For this purpose,l I prefer to.y utilize :a spring pressed VVdogf thattmoves g automatically .to

:inxgtrucksbfithisclassxso thatsthetruck'is Venabled 5 Vdog thedetent in release position, thisf.dog;.allow in-.tthe' normakvertical :range of` the liftingcaring `the detent to move to a holdingy positiorrwhen :riage -tovhandlenloads :atia higher elevation than engaged by a-trip blockthatfmoves vertically-'With .would otherwise benpossible. 'i This isA accomthe lifting member. i'plishedithroughanzassembly havingv automatic 10 Ihave thus -outlined=rather 4broadly.fthefmore 'detent'means'fforf adjusting each lifting member important features ofanyrinventionfiniordenthat arid-'holding' thesaid rlifting member in/anupper the-detailed description :thereof that ffollowsym'ay vposition-'r'elatively tol-its ynormal lower position on be better understood, and in order thatvmyfcon'- rLthe :car-riage;A and-iii:V is `to an assembly of this detribution .to the art mayi befbetterappreciated. scriptions that;my.inventionparticularly relates, Y15 yThere are, of cou-rseV additional featuresgofmy "f'fItahas been propos'edlto utilize as detent that is invention that will :be describedhereinafter, and pivoted-onlaf'liftingcarriagelforadjusting and which will form the subject of fthe-claims-ap- Iholding-1 afrlifting memberfrelativ'elyto the carpended hereto. -Those skilled inthe art will-,apriage. Howevenvthe.pivot-pointeof thefdetent preciate that the conceptioneouWhichf-my dis- :musbgmmgstdirectlyover*thelifting member 20 closurev is based may readilybeutilized asa basis vivherebyto preventthewei'ght-of the-'liftingmemfor thev designing of= other structures for carrying -ber`f from 'throwing' ``the-detentfout 'of supporting out the several purposes. of my invention. It is engagement Withf-this member, This construcimportant, therefore.; that ithe claimszbe regarded tion'. limits 'the possibleffmovement'of the lifting asfnellldhg Sblehl equivalent` constructions; 3S d0 member relatively to 'the carriage because a part 25 not depart from`thevspiritandI scope ofmy inof the'fdetent is always-in thepath of the lifting ventiOn, -in order toypreventztheappropriation of my inventioniby those skilledfin-the art.

IAs-a 4feature ofmyf-invention; I contribute in an vJRlefel'IiIlg' 110W t0 .thefdrawings assemblyA ofthe 'class described anovel automatic *Fig lis a side view showing a preferred Aform detente-means that allows vunrestricted rmovement 3L of. my kinvention with the liftingmembers shown ofthe lifting member relatively tothe carriage in by `full lines'ina lower position and inbreken a' verticaldirection. {Morel particularly; I utilize :lines in anupper position.

a-detentthat; when releasingthe'lifting member, z' Fig: 2;is.a frontview of parts `shown inVV Fig; 1. 'moves' entirelyjout ofi the;` path of the vertical fFig.f3-is a-plan view..of.the structure oflFig; 1. movementv of the fliftingmember. I- accomplish .35 .rFigsAg 5; 6; 'uandr aredetail views illustrating this by pivoting lthe detent on an axis that is out of the cycle of operationof myinvention. thejpathin whichtheload"-lifting*memberA moves, Fig.y 9- ris a 'sectional' view onthe line"9--9Al of Withonly. a"portion'fof"thef'detent"entering this Fig; 4.

`path tosupport the liftingmember relatively to In 'the drawing,V I have :indicatedfgenerally by the carriage. r'Preferablyl pivot the detent. atits 40 thenumerall theadjustablefmounting means lower end; and in the particular arrangement, the thatserves in my. inventionto support 'the loadlWeight of the load-lifting lriernloei.k holds thedelifting member upon .thelifting 'carriage' of the tent in engagementvvith it because of the position truck. Actually, in the example "illustrated, a of thepvot axis. Ifurther utilize means for pair of the mounting v-means l0.v is vutilized to actuatngthe detentthat doesnotpbjstruct the A45 support a' pair of loadliftingmembers that are movement of; ,'the lifting member..,and` for this in the form of forks l l, butfitris to'be understood purpose I prefer to locate the actuatingmeans that'my invention-isunot"flimitedlto the'use of at the side of the lifting member. l',Iflfiis.constructwo forks or to..-.any.'part-icular A.form of loadtion enables `me to facilitate the assemblyof the engaging'member. :'Beeause themountingmeans lifting member to'thecarriage because `thedetent 50 HIy are duplicatesein construction; lL shall gener- 'meanipermits,lhejflftllgmember :liebe inserted ally refer to only one of the mounting means'in longitudinally into. guidespnthe. carriage, k..f.A1so, the following description. Theliftingcarriage Icantherebyprovide,more.thanoneof.thedetent is indicated by thenumeral: liand isoffthe type :means.forfiholdingathe-.liftingmember in vmore that'has4 a.verticalfrontfplate I3..for,the mount- 55 ingg-.of sui-table load-.handlinm 'apparatus tobe lifted on the carriage, and that moves vertically along truck uprights I4 relatively to which it is guided by rollers I5. However, the particular structural details of the carriage I2 and the means whereby it is moved vertically are not important to an understanding of my invention, and it is merely necessary to know that the carriage I2 moves vertically to lift a load-engaging member that is adjusted relatively thereto through the means I0.

Each of the mounting means I has a vertical guide member I6 that guides one of the forks II so that it may slide vertically relatively to the lifting carriage I2. For this purpose, I make the guide member I6 channel-shaped in cross section, thereby providing inwardly turned nanges I1 that are engaged in grooves in opposite edges of a vertical arm I8 of the fork, as shown in Fig. 3. Secured integrally' to the back of the guide member I6, as shown in Fig. l, are an upper clip I9 and a lower clip 20 that engage over the upper and lower edges of the front plate I3 of the lifting carriage so as to support the guide member I6 upon the carriage, as will be understood by those skilled in the art. To support the fork II in its normal lower position relatively to the lifting carriage I2, a stop block 2| shown in Figs. l and 2, is attached to the front of the guide member I6 at its lower end, this block 2I engaging a block 22 on the vertical arm I8 of the fork. Actually, the mounting means I0 may be considered a part of the lifting carriage I2, for the purposes of my invention.

I shall now describe the extremely novel detent means whereby I hold the fork II in an upper position relatively to the lifting carriage I2. As shown in Figs. l, 3, 4 et seq., an intermediate portion of the guide member I6 carries a pair of rearwardly extending vertical bracket plates 23 on which is mounted a transverse pivot shaft 24. Fixed upon this pivot shaft between the bracket plates 23 is a detent 25, and an upper portion 25a of this detent 25 swings about the pivot axis between holding and release positions relatively to the vertical arm I8 of the fork. The detent 25 moves in a clearance hole 26 in the back of the guide member I6, as best seen in Fig. 9, and when the fork moves upwardly relatively to the lifting carriage I2, the upper portion 25a of detent 25 moves under an abutment 21 in a notch formed in the back of the vertical arm i8, as may be seen in Figs. and 6. The fork must thereafter move vertically with the lifting carriage i2. It will be understood that movement of the fork II to its upper position relatively to the carriage I2 may be very conveniently accomplished by moving the carriage I2 downwardly relatively to the fork II while the said fork I I is held against downward movement.

It is well to note at this point that the detent 25 can move entirely out of the path of movement of the vertical arm I8, as shown in Fig. '7, and this detent 25 therefore does not restrict the possible vertical movement of the fork II in the guide I5. Further, because of the position of the pivot shaft 24, the detent 25 when in holding position is inclined upwardly and toward the vertical arm I8 of the fork II, and I am enabled thereby to utilize the weight of the fork II to hold the detent portion 25a engaged with the abutment 2l.

I provide also novel means for releasing the fork II from the detent 25 when it is desired to move the fork to its solid line position of Fig. l relatively to the lifting carriage. Thus, I mount a cam lever 2S upon one end of the pivot shaft 24 in a position at one side of the guide member I6 and the vertical arm I8 of the fork. Upon the side of the vertical arm I3 is a trip block 2Q that is so located as to engage the end of the cam lever 28 and swing it upwardly, as in Fig. '7, when the fork is lifted relatively to guide member It. This action rotates the pivot shaft 24 to swing the detent 25 entirely away from the abutment 21, and causes the detent to be positively locked in this position by a dog 30 that is mounted below the cam lever 28 through a pivot pin 3I on one of the bracket plates 23. The actual locking action is performed by a spring 32 that swings the dog 3U in such a way as to cause a nose 33- on the dog to intercept a shoulder 34 on the cam lever 28. The spring 32 is attached at opposed ends to the dog 3G and to the cam lever 28, and not only serves to operate the dog, but is also instrumental in causing the detent 25 to engage properly with the abutment 21.

The dog 3() is actuated to release the cam lever 23 during the subsequent downward movement of the fork, as in Fig. 8, thereby conditioning the detent 25 to engage the abutment 21 upon a later movement of the fork to its predetermined upper position relatively to the carriage. This releasing action of the dog 3i! is effected by trip block 29 contacting the lower end 35 of the dog 3B. Thus, Fig. 8 shows the trip block 29 engaging part 35 of the dog 3) and about to move the nose 33 away from shoulder 34, so that the detent 25 will be released for movement'toward the position of Fig. fi. In thisv position, the detent portion 25a is of course pressed against the vertical leg I8 of the fork through the action of the spring 32, and will engage abutment 21 when the fork is again moved to its upper position relatively to the lifting carriage I2.

I have alreadyl indicated that the detent 25 allows unrestricted vertical movement of the fork I I, and it will now be observed also that the cam lever 28 and the dog 3G do not interfere with this movement. The said lever 2B and dog 30 do coact with the trip block 29, but nevertheless can move out-of the path of this trip block as the fork II moves vertically. I am thereby enabled to assemble the fork II to the guide member I6 merely by sliding the vertical arm I8 of the fork downwardly into the guide member I6. Further, my novel detent mechanism is well suited for mounting at an intermediate point in the vertical movement of the fork, and therefore it is possible to utilize this mechanism at various points along the length of the vertical guide member I6 so as to support the fork II in more than one upper position above its normal lower position relatively to the lifting carriage I2. I-t is conceivable, of course, that the parts of my novel mechanism could be reversed from the positions that I have particularly described, with the detent 25 mounted on thelifting member I and the abutment 21 formed on the guide member I6.

It is believed that the construction and operation of my novel adjustable fork assembly will now be understood, and that its considerable advantages will be appreciated by those skilled in the art.

I now claim:

l. In an assembly of the class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to said lifting carriage in a vertical path, a detent member mounted on said lifting carriage for movement relatively to the vertical path of said lifting member into and out of a l holding position aipart. of said :lifting/member with` which said 'detent member coacts1.--when:in holding position to support: saidlifting member i- .on` said lifting carriage, a-cam throughwhich said lliftingf. member when movingupwardly relatively said .carriage movessaiidl dog toallowsaiddetent;

member :to: move to holdingposition.

1E 2j In an assembly ofthe class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to isaid' li, ting-carriage in a verti-Vv cal path, a detent member, means mounting said detent member on said lifting carriage for movement relatively to the vertical path of said lifting member into and out of a holding position, a part of said lifting member with which said detent membei` coacts when in holding position to support said lifting member on said lifting carriage, a cam for said detent member, a surface on said lifting member coacting with said cam when said lifting member moves upwardly rela-V tively to said carriage to move said detent member to a release position entirely away from said vertical path, a dog for said detent member, means moving said dogr when said detent member moves to release postion to lock said member in release position whereby to allow unrestricted movement of said load-lifting member both upwardly and downwardly relatively to said lifting carriage, and a surface on said lifting member moving said dog relatively to said detent member when said lifting member moves downwardly whereby to allow said detent member to move to holding position.

3. In an assembly of the class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to said lifting carriage in a vertical path, pivot means on said lifting carriage, a detent member mounted on said pivot means for movement of its upper portion relatively to the vertical path of said lifting member into and out of a holding position, a part of said lifting member with which said detent member coacts when in holding position to support said lifting member on said lifting carriage, a cam through which said lifting member when moving upwardly relatively to said carriage moves said detent member to a release position entirely away from said vertical path, a dog acting when said detent member moves to release position to bold said member in release position whereby to allow unrestricted movement of said load-lifting member both upwardly and downwardly relatively to said lifting carriage, and means through which said lifting member when moving downwardly relatively to said carriage moves said dog to allow said detent member to move to holding position.

4. In an assembly of the class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to said lifting carriage in a vertical path, a detent member, pivot means mounting said detent member on said lifting carriage, an upper end portion of said detent member moving into and out of a holding position Gil path of said liftingfmemberwhereby theA weight -ofsaid lifting member acts through the said :part toA maintain the upper end of thel detent member in holding position, a cam throughwhich saidrlifting member when moving upwardlyf'rela- Vtively to said carriage moves saiddetent member toa.` release position, adog acting whenr'said detent-member'moves to release position to flock :said member in release position Wherebyrta-,allow downward movement of said load-lifting :member relatively to said carriage, and means through which said lifting Amember.when moving `downwardly relatively to the carriage moves the dog to allow the upper end portion of said detent member to move to holding position.

5. In an assembly of the class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to said lifting carriage in a vertical path, a detent member, pivot means mounting said detent member on said lifting carriage, an upper end portion of said detent member moving into and out of a holding position relatively to said lifting member as said detent member moves on its pivot means, a part of said lifting member lwith which the upper end portion of said detent member coacts when in holding position to support said lifting member on said lifting carriage, said pivot means being positioned with its axis at one side of the vertical path of said lifting member whereby the weight of said lifting member acts through the said part to maintain the upper end of the detent member in holding position, a cam through which said lifting member when moving upwardly relatively to said carriage moves said detent member to a release position entirely away from said vertical path, a dog acting when said detent member moves to release position to hold said member in release position whereby to allow unrestricted movement of said load-lifting member both upwardly and downwardly relatively to said lifting carriage, and means through which said lifting member when moving downwardly relatively to said carriage moves said dog to allow said detent member to move to holding position.

6. In an assembly of the class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to said lifting carriage in a vertical path, a detent member, pivot means mounting said detent member on said lifting carriage, an upper end portion of said detent member moving into and out of a holding position relatively to said lifting member as said detent membei` moves on its pivot means, a part of said lifting member with which the upper end portion of said detent member coacts when in holding position to support said lifting member on said lifting carriage, said pivot means being positioned with its axis at one side of the vertical path of said lifting member whereby the weight of said lifting` member acts through the said part to maintain the upper end of the detent member in holding position, a cam through which said lifting member when moving upwardly relatively to said carriage moves said detent member to a release position, a dog for said detent member,

means moving said dog to lock said detent member in release position when said member moves to release position, and a portion of said lifting member engaging said dog when moving downwardly relatively to said lifting carriage to move said dog out of locking relation to said detent member whereby to allow said detent member to move to holding position.

7. In an assembly of the class described, a lifting carriage, a load-lifting member, means mounting said load-lifting member for movement relatively to said lifting carriage in a vertical path, a detent member, pivot means mounting said detent member on said lifting carriage, an upper end portion of said detent member moving into and out of a holding position relatively to said lifting member as said detent member moves on its pivot means, a part of said lifting member with which the upper end portion of said detent member coacts when in holding position to support said lifting member on said lifting carriage, said pivot means being positionedwith its axis at one side of the vertical path of said lifting member whereby the weight of said lifting member acts through the said part to maintain the upper end of the detent member in holding position, trip means moving with said lifting member, a cam through which said trip means when moving upwardly relatively to said carriage moves said detent member to a release position, a dog for said detent member, means moving said dog to hold said member in release position when said member moves to release position, and said trip means when moving downwardly relatively to the lifting carriage moving the dog out of locking relation to the detent member to allow the detent member to move to holding position.

No references cited. 

